Many types of hose are formed on mandrels, for a variety of reasons, among which are the fact that hose of very large diameter and/or wall thickness and hose comprised of a plurality of layers of different material make other methods, such as extrusion, impractical. Even some extruded hose is formed using a mandrel to provide adequate shaping support during cooling.
Formation of hose on a mandrel is typically done in the following manner:
The mandrel is usually a rod of circular cross-section and of the order of 25 to 100 feet in length. For multi-layer hose, an applicator assembly (wrapper, extruder, etc.) applies each layer one at a time on the mandrel. Layer may be comprised of a resilient material (i.e., rubber), cloth, metal wire or braid, cloth strips or threads, etc.
After the last layer is formed, the resulting hose structure is cured to "fuse" adjacent layers of resilient material to one another. After "curing" the hose is allowed to cool and is then "stripped" (i.e. removed) from the mandrel.
The stripping operation is a tedious, time-consuming activity. One technique employed is to provide radially aligned holes at a plurality of locations along the mandrel and communicating with one another by a common axially aligned hole provided in the mandrel. Air under pressure is provided to "break" the hose away from the mandrel. This arrangement provides the hose with an undesirably rough interior surface. Also the resilient material may tend to enter the holes and thereby block air from entering the region between the hose and the mandrel. Also the holes which are exposed as the hose is moved axially along the mandrel tend to release the maximum amount of air under pressure resulting in significantly reduced air pressure being directed to those holes still lying beneath the hose, thus reducing the effectiveness of the operation.
Another technique employs a mandrel having elongated grooves extending parallel to the longitudinal axis and along the surface of the hose. This technique suffers the same defects as the prior technique described above. It thus becomes important to provide a technique and apparatus for simply and rapidly removing hose from a mandrel having a smooth finished outer surface.